RTEC / Dyno Session June 1998

This page shows the different results from the dyno-sessions. Fortunately, almost every dyno available in Switzerland is an AWD type. DIGIT POWER, a well known tuning shop in Switzerland (Carlsson, Porsches, etc.), owes a Bosch AWD dyno that can be controlled remotly from the drivers seat during running the car on it. The testing procedures are not only simple pulls furthermore it also alows to test the cars behaivour on any rpm level by increasing the resistance and therefore the load of the engine.

On the last dyno at June 3rd we had a seesion for about 2 1/2h ! We dialed the APEXi Super AFC and checked the fuel delivery, checked the cars behaivour at different rpms, increased, reduced boost, played with the Blitz limiter, scrambeling, and much, much, much more. Unfortunately, we haven't stored all data in the dyno computer as the memory would have an overflow, but we just replotted the most important ones (unfortunately with the wrong y-scale).

The following sections discribe the test scenarios and some conclusions we came between the tests. Of course these are the results on my car. Other cars my behaive different and therefore these figures show general differencies between settings and mods. If you have any question, feel free to ask and send me an email.

The AWD Dyno at DIGIT POWER is a Bosch type that allows testing up to 1100hp and is settable for front, rear or all-wheel drive. For this the rolls are adjustable and can be set to almost any lenght of the wheel-distances. HP, tourque, speed, resistance and other parameters are visible in real time on the monitor while the system is controlled remotely from the drivers seat.

The room is also equipped with a huge fan that allows to cool the engine for more accurate readings and to keep the colling system alive :) This fan-system is also controlled by the dynos computer and regulates its speed.

At this session the fans air-temperature was around 22°C (71.6°F) while the ambients reading went up over 31°C (87.8°F). Of course lower temperatures would give much better readings but this is close to what we have on the streets in Spring and Summer.

Please note: The HP figures are measured by the new EU guidelines and show about 10hp less than DIN and are also about 15hp lower as standard US dyno readings.

Three years ago the Bleeder Valve mod was done by DIGIT POWER and got tested on their dyno. Today with the same valve the boost shows still about 0.7bars (10psi). This picture shows the data I read out of the sheet as the original is unscannable. Please deduct about 10hp from the reading to compare with the new readings.

The stock corrected engine horsepower was around 284hp with stock boost of 0.45bars (6.5psi). At 0.7bars we got about 352hp and 395ft-lbs

Since then the car made about 55'000km, got two trannies and two clutches but feels still good. At this point we made a test run by setting the Blitz DSBC to OFF and reinstalling the bleeder valve as well as the stock solenoid wastegate actuator valve. The mods are :

- Bleeder valve (0.7bars)
- K&N FIPK
- ATR Downpipe
- ATR highflow catalytic converter
- BORLA Cat-Back exhaust
- HKS SBOV

The dyno result was dissapointing ! Unfortunately I lost that sheet (we throw some away and some have not been printed) but I remeber it very well :

As we had only about 10°C air temperature three years ago some loss of about 12hp (calculated by the dyno computer) is possible. But there are still 11hp missing. After figgeling around with the AFC by measuring fuel pressure and exhaust temperature (at the ATR cat) we got them back (uff!) At this point we did not subtract the 10hp difference between the mesuring method.

The more interesting thing is the loss in tourque. Even with 0.7bars of boost we got lower tourque than with the stock setup (0.45bars) and the stock exhaust parts. WHERE DID I LOST THIS TOURQUE ?

After running some more test and the discussion afterwards with the mechanic of DIGIT POWER (I wish I would have that knowledge), we discovered that if you run stock turbos and some more boost (e.g. 12psi), a high-flow filter, downpipe, high flow cat and exhaust DO NOT ADD YOU ANY HORSEPOWER OR ANY TOURQUE !!! The positive thing is, that power is better in the lower band and rises earlier but not as expected. The tuning specialist told me due to his experience with this carst the stock DP and the exhaust are NO RESTRICTION with stock turbos ! Even with the next bigger Turbos (13g) the bone stock exhaust is null problemo as the problem sits elsewhere (later). This, of course, is different with much bigger turbos (T56 Garret ?)

The dyno really shows that I lost some power/tourque due to the new exhaust. The G-Tech meter told me the same times before and after this and I also felt something like turbo-lag. It just took longer till the power came back after shifting up. But when running trough the band (w/out shifting) power is better. Therefore the exhaust upgrade (DP,cat,exhaust) must be an investement in the future, i.e. I'm now prepared for big Turbos :)

I changed the Blitz DSBC settings to the well know parameters that gave me that great performance during the last weeks. We also removed the bleeder valve and unplugged the stock solenoid wastegate actuator valve. The mods are now :

- Blitz DSBC
- Apexi S-AFC (no settings at this moment)
- K&N FIPK
- ATR Downpipe
- ATR highflow catalytic converter
- BORLA Cat-Back exhaust
- HKS SBOV

We pulled it and the display showed amazing 468hp at 5500rpm (not plotted as we had the wrong scale set on the printer, LOL) but dropped rapidly after that peak. Tourque was around 460ft-lbs at 4800 rpm !!! I felt great and my smile was as big as I just killed a Viper and an 911 Turbo at the same time :))

Unfortunately the tuning guy was not that amazed as I was. He looked at me and said : "Your car knocks heavily and the ECU cannot retard the timing fast enough due to the fast boost rising". The dyno curve on the screen showed this as power was lost heavily at 5600 (retarded by at least 10°). Do you guys remember a loss of boost or a boost-waving at high rpms ? NOW YOU KNOW YOUR CAR IS KNOCKING and timing is retarded due to this. You are loosing horsepower as well as this will badly hurt your engine !

Of course I expected a very lean condition that causes knock but the attached meters showed a rich mixture ????? This told us that even on boost around 1.3bars there was always enough fuel and even we where able to lean it out by 10% at 5600 with the help of the AFC ! But this didn't changed the behaivour. Again, we have no plots on this as we sat in the car, changed parameters and watched the screen in the hope for better figures. The tuning shop made some 3S, Supras and others and added 15gs and he told me that there was no need for bigger injectors until boost went higher than 1.4 bars ! Also with the bigger turbosit was not necessary to get higher than 1.3bars as the power was about 500hp at 1.2bar and stayed there up to the redline ! I guess that with more than 1.3bars our cars are in the need for the fuel-pump and bigger injectors as well as the VPC. Remember my unhealthy 468hp with 1.25bars and with the stock turbos ! There's a lot potential in the car.

Dyno testing the car with different Boost settings to get rid of the knock

Again the hp scale is wrong but you can see the negative peak in the tourque curve as well. At this time boost was set to a low 1.12bars. Here we noticed that the timing retard became lower than 10° and therefore knock is getting lower :( Unfortunately also hp/tourqe are lower ! The plot below shows the figures : Tourque 425.1 ft-lbs@4180rpm and 385.3hp@5110rpm. Remeber the retard we got and therefore less hp than expected. Tourque was fine here.

The next plot shows the proper curves without any retard (Boost at around 1.05bars).

I'm still looking for a good way to combine both scans that you can see the difference. For now just let me explain what happend: After reducing the Blitz settings the tourque curve was shifted to the right. Look closely at 3000rpm. The "bad" curve showes a flatter curve that ends in higher overall tourque and peak (425ft-lbs) while the "good" one rises very fast but stays on lower overall tourque. Watch the curve at 5000. Here both curves have the same value but the "bad" falls down quickly due to the retard. Here the boost meter showed the wavy behaivour.

Finally, we ended up in a power curve close to knock but without any timing retard. Please note that this is continous boost as overboosting for a second caused no problems.

Another big adavantage of having a dyno is to hold the car running on a specific rpm and change the paramters on the fly with an immediate response. The dyno than increased the resistance of the rolls that allowed to hold the specific speed easily. We did this with the S-AFC as we measured the exhaust temperature and mixture on the rpm-level provided by the AFC. The optimal settings showed that we have been able to enlargen the mixture in the lower rpm range but also to richen it at the upper range. The picture shows the current AFC settings :

After this we haven't found any new peak in tourque or hp but the curve went flatter (usually higher) and raised sooner as before. The final plot below shows the hp/speed curve in 4th gear. The readable curve is measured at the wheels and shows a loss of 56.2hp due to the tranny ! This is about 14.3% and less than expected.

1. Plug gap
The plugs were just changed before the test (NGK) and gapped to 0.91mm (0.036"). But the mechanic as well as Brian from GT Alley told me to gap them down to 0.71mm (0.028") for high boost applications. I'll do this and dyno it again. I wonder if anything changes in the behaivour and also if knock will be getting lower.

2. Bigger Turbos and exhaust manifold
I'm planning in getting bigger turbos and also the exhaust manifold. This combination makes sense as a better designed manifold can help to reduce pre-turbo pressure and excessive heat that can hurt the engine and also causes the high-speed knock. With them I'm expecting more power at the same boost as well as the ability to boost up to 1.2 bars or higher.

3a. Fuel upgrades
The stock fuel system seems to be able to work up to 1.25bars without having a problem. Especially as the measurings showed a richer condition around the hp peak as expected. With the help of the S-AFC this can be leaned out more by about 4% to run into the fuel cut later. Nevertheless, with bigger turbos the boost may be risen to a higher level and then the fuel system will be at +100%. Time for bigger injectors, a VPC with custom chip and a bigger fuel pump.

3b. ECU upgrade
At the same time, an upgraded ECU will find its way into the car. This to change the ignition timing, fuel maping and fuel cut for the new setup.

So, stay tuned for more information on dynoing the 3000GT TT on different power setups :)